Small Engine Troubleshooting Problems? Ask a Mechanic Now.
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When you put the engine back together did you align timing marks on the crankshaft and the camshaft? If not that is your problem, the engine is out of time internally.
The only other thing that would cause this is if the flywheel key is sheared. On the new electronic ignition coils even if the flywheel key is sheared you will still get spark it will just be out of time there as well. As long as you are sure that the timing marks on the crankshaft and camshaft are lined up correctly then I would check the flywheel key. Those are the only two things that would or could cause the problem you are describing.
There is no other way that you can have the problem that you have presented unless one of the two things are off or wrong.
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